reserve x,y for set;
reserve a,b for Real;
reserve i,j for Integer;
reserve V for RealLinearSpace;
reserve W1,W2,W3 for Subspace of V;
reserve v,v1,v2,v3,u,w,w1,w2,w3 for VECTOR of V;
reserve A,B,C for Subset of V;
reserve L,L1,L2 for Linear_Combination of V;
reserve l,l1,l2 for Linear_Combination of A;

theorem
  Z_Lin(A /\ B) c= Z_Lin(A) /\ Z_Lin(B)
proof
  Z_Lin(A /\ B) c=Z_Lin(A) & Z_Lin(A /\ B) c=Z_Lin(B) by Th13,XBOOLE_1:17;
  hence thesis by XBOOLE_1:19;
end;
